1. Field of the Invention
Embodiments described herein relate to roomside replaceable fan filter units. More particularly, embodiments described herein relate to a roomside replaceable fan filter unit with an aerosol injection ring.
2. Description of the Related Art
Cleanrooms are utilized in many industries, for example pharmaceutical manufacturing facilities or biotechnology research labs, where clean space is a manufacturing or health-related requirement. A plurality of filters, typically mounted in the ceiling of the cleanroom as roomside replaceable filter units, are configured to remove particulate from air entering the cleanroom at a predetermined efficiency selected based upon the cleanliness requirements of the activities performed in the cleanroom.
The performance of the filters disposed in the roomside replaceable filter units is critical to for providing contaminant-free or hazardous-free air. Therefore, it is necessary to certify the performance (e.g., leak and/or filtration efficiency) of the filters by field testing on at least an annual basis to determine whether the filters are maintaining the proper filter efficiency. The certification process ensures that the filters are meeting predefined operations criteria and/or standards.
Typically a certification process includes challenging the filters with an upstream aerosol challenge to perform statistically valid tests. Most cleanrooms are configured to have a common plenum feeding multiple roomside filter units. In order to test one filter, enough aerosol must be provided to the entire plenum to have a sufficient uniform concentration for testing the filter. As such, large quantities of aerosol are needed to create a uniform concentration of aerosol within the plenum. The large quantity of aerosol needed to test a single filter is not only wasteful, but also undesirably loads the interested filters in communication with the plenum. Additionally, an undesirably high usage of aerosol, a long period of time is required to adequately charge and stabilize the aerosol concentration within the plenum, which undesirably reduces the availability of the clean room for normal operations.
Thus, there is a need for an improved roomside replaceable filter unit and method for testing filters used in the same.